Ultraflux Uf 841, User Manual

Page: 49 / 105

49
NT UF 841 CP GB (d) / June 2015
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Fault: Depending on the polarity chosen (NO: normally open, NC: normally closed), the relay
changes state when the associated fault occurs.
In the example, the variable selected is "general Q". This means
that the relay closes when the flow meter is not measuring a flow
and remains open otherwise.
•
Direction: Depending on the polarity chosen (NO: normally open, NC: normally closed), the relay
changes state when the sign (+ or -) of the associated magnitude changes.
•
Threshold:
Depending on the polarity chosen (NO: normally open, NC: normally closed) and the
direction in which the threshold is crossed, the relay takes one state if the value is greater than the
indicated threshold. The relay switches to the opposite state if the value concerned is lower than the
threshold.
Comment: In order to restrict the relay backlash when the dimension concerned fluctuates around
the threshold, hysteresis must be defined.
The diagram below illustrates this principle with hysteresis at 2 % and the threshold crossed in the
ascending direction:
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Frequency:
The frequency at which the relay is opened and closed depends on a value to be
defined. Example: high flow, high frequency, low flow, low frequency.
The following must be defined:
o
the parameter that the output represents.
Select the magnitude that you wish to associate with the
output using the chapter headers (function) and the chapter
items (value).
o
the value relating to 0 hertz.
o
the value relating to 1 Khertz.
o
the value if a fault occurs.
Off
On
On